Friday, December 21, 2007
Motorcycle
Motorcycle usually refer to a self propelled two-wheeled vehicle, most commonly powered by gasoline-fueled internal-combustion engine. There are exception, such as the occasional electrically powered bike and certain open three-wheeled vehicles that fall into the same category. Include as well as motor scooters, characterized by medium-sized engine (averaging about 200 cc) and fitted with relatively wide, small diameter wheel.
Motorcycle History
Some of the earliest motorcycle experiments involved fitting steam engines to modified bicycles. Not until the advent of the gasoline engine, however, did motorcycle design assume serious and practical forms. Man who start to modify become a modern motorcycle are Nikolaus A. Otto, he developed the concept of a four-stroke engine, and Gottlied Daimler, who use Otto’s idea and in 1885 built a motorcycle powered by a single-cylinder air cooled engine, which developed one-half horsepower. Hildebrand brothers of Munich called their design a Motorad, the first commercial practical with water air-cooled, 1488 cc, four-stroke, two cylinder engine, it was capable of approximately 40 km/h (25 mph).
Several technical problems remained, including the lack of an effective means of transmitting power to the driving wheel. Customarily, a leather belt was employed, but this tended to slip when wet, and it frequently broke because of the jerky power impulses of early engines.
About 1900 a steel chain use to change a leather belts for power transmission. Disc brakes were employed on the motorcycle built by the Imperial Company of Great Britain as early as 1901. Overhead cams and valves, fuel injection, multi-gear transmissions, shaft drive and telescopic suspension all appeared prior to 1918.
Modern Motorcycle
Modern motorcycle have become lighter, faster and very specialized. Today a typical street bike has four cylinders with four carburetors, cast-aluminum wheels, at least one disc brake, a 5 or 6 speed transmission and a sophisticated electronic ignition system. Most larger street bikes are powered by four-stroke engines. Dirt, or off-road, bikes, on the other hand, typically have two-stroke, single-cylinder engines, although four-stroke single are regaining popularity.
National governments generally prescribe a certain equipment standards for motorcycles used on the streets. For example, in United States electrical switches and lighting equipment, hydraulic hoses and brake, tires and many other items must meet strict federal requirements.
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